1. Field of the Invention
The present invention relates in general to bore gauges and in particular to an apparatus for measuring the inner diameter of bores.
2. Description of the Prior Art
In the machining of precision parts, it is often necessary to measure the inner diameter of a machined bore in order to determine when the part has been machined to its finished dimensions. Many devices are known in the art for achieving this inner diameter measurement. For example, U.S. Pat. No. 3,081,548 to Schwartz discloses a bore gauge utilizing a pair of caliper arms which move arcuately with respect to the axis of the gauge. An actuating means causes a dial indicator to indicate the longitudinal displacement between the caliper arms and the calibrations on the gauge, which displacement is related to the inner diameter of the bore. Other bore gauge devices are described in U.S. Pat. Nos. 1,511,624 to McGuckin, 2,558,291 to Eisele, 2,771,687 to Hutto, Jr., and 3,995,374 to Fisk.
U.S. Pat. No. 1,591,259 to Ames discloses a tool for setting or checking measuring instruments, such as cylinder gauges, for predetermined sizes. The setting tool includes a dial indicator which is calibrated between adjustable and accurately positionable fingers by a plurality of spacing members such that the distance between the fingers is exactly equal to the diameter of the bore to be measured. A cylinder gauge is then positioned between the fingers and adjusted so that the indicating hand of the dial indicator will register zero. When the cylinder gauge is inserted in the bore of a cylinder to be measured, the dial of the indicator dial will show the amount of over or under size in the cylinder as compared to the distance between the fingers of the setting tool.